Many indoor sports require a playing area which is relatively large, and certain of these, such as tennis, require additional space, for example, a run-back area, which may be larger than the playing area itself. The provision of such a relatively large area which is maintained solely for the playing of a single sport is therefore extremely wasteful of space and is economically undesirable.
Accordingly, there has been a tendency, in most recent times, to provide multi-functional indoor sports arenas. However, this solution has its own inherent disadvantages. Firstly, the line markings for each sport are, to all intents and purposes, permanently visible. Thus, it is customary for the demarcation lines for each sport to be in the form of strips of plastics material which are applied to the floor of the area by means of an adhesive. The strips are provided in different colours so that, for example, white strips demarcate a badminton court, whilst red strips denote a basketball court. However, there are numerous instances where a large number of different coloured lines are present in a small area and this is highly likely to cause confusion in the mind of a player.
An alternative method of providing line markings for a number of different sports in a single playing area is to employ a translucent playing surface with the demarcation lines of the playing area being located beneath such surface and being illuminated by strip lighting from below the line. This solution is, however, extremely expensive and, in many situations, is not economically viable.
The use of laser beams to produce visible line markings is known. Thus, for example, in U. S. Pat. No. 3,741,662, there is disclosed a method of providing a constant wall of visible light for visually demarcating a scoring or score-advancing line wherein movement through such wall is of significance in playing the game. In such method a laser beam is directed horizontally from outside the playing area and is reciprocated vertically to create and maintain the vertical wall of light.
In U. S. Pat. No. 4,090,708, a number of somewhat similar arrangements are disclosed. In a first embodiment, this prior specification provides a single laser beam having a luminous horizontal segment directed across the playing area which acts as an overhead line of demarcation in combination with a relatively lower parallel luminous segment of the same beam which is reflected reversely across the playing area to provided a ground-level demarcation line. Alternatively, two oppositely travelling light beams having a pair of horizontal luminous segments serve as a composite overhead demarcation line. These are employed in combination with a second pair of horizontal, relatively lower, luminous segments of the same beams which serve as a ground-level demarcation line.
Neither of these prior specifications is of particular relevance to the present invention in that they are chiefly concerned with identifying particular situations occurring during the playing of the game, such as the attainment of first-down yardage in American Football or whether a ball lands in or out of court during a game of tennis. Neither prior specification discloses, or even considers, the possibility of utilising laser technology to define the actual playing area. It therefore follows that neither specification even remotely considers the use of laser technology to provide demarcation lines on an otherwise unmarked area, which demarcation lines can be varied almost at will and extremely rapidly.